An inductor, which is one of the chip electronic components, is a representative passive element forming an electronic circuit together with a resistor and a capacitor to remove noise. The inductor is combined with the capacitor using electromagnetic properties to configure a resonance circuit amplifying a signal in a specific frequency band, a filter circuit, or the like.
Recently, as miniaturization and thinness of information technology (IT) devices such as various communications devices, display devices, or the like, have been accelerated, research into a technology for miniaturizing and thinning various elements such as an inductor, a capacitor, a transistor, and the like, used in the IT devices has been continuously conducted. The inductor has also been rapidly replaced by a chip having a small size and a high density and capable of being automatically surface-mounted, and a thin film inductor in which a mixture of magnetic powder and resin is formed on a coil pattern formed on upper and lower surfaces of a thin film insulating substrate by plating has been developed.
In the thin film inductor, after the coil pattern is formed on the insulating substrate, an insulating film is formed thereon so as to prevent a contact between the coil pattern and a magnetic material.
However, in a case in which an insulating body is formed by a lamination method, or the like according to current technology, the insulating film needs to have a sufficient width in order to form the insulating film to be extended up to lower portions of coil portions. As the width of the insulating film becomes large, a volume occupied by the magnetic material is reduced, resulting in a reduction in inductance.
In addition, the insulating film has not been partially formed around the lower portions of the coil portions to thereby create voids. Because the voids in which no insulating film is formed cause the coil portions to directly contact a metal magnetic material, or the like, a leakage current is generated. As a result, inductance has been in a normal state at a frequency of 1 MHz, but has been rapidly reduced at high frequency, thereby creating a poor waveform.
The following Patent Document 1 and Patent Document 2 disclose a thin film inductor in which an internal coil pattern is formed on upper and lower surfaces of an insulating substrate by plating. However, there is a limitation in forming a thin insulating film without any void, by only using the processes disclosed in Patent Document 1 and Patent Document 2.